Disk Utility Icon

Testing and repairing a disk or volume

If you have problems with a disk or volume, you can use Disk Utility to test and repair it. Disk Utility verifies and repairs partitions, the layout map of the disk, and the disk's directory structure.

Occasionally, ownership and permissions of files or folders on a disk might become incorrect, preventing a file or application from opening. You can use Disk Utility to verify and repair permissions on a disk installed with Mac OS X.

To repair a disk, you may need to enter the password for an administrator. If you aren't logged in as an administrator, enter an administrator's name and password when you are asked.

You cannot repair your startup disk unless you start up using a different disk. See "Testing and repairing your startup disk." In addition, you cannot test or repair write-protected disks, nonrecordable CDs or DVDs, or disks with open files.

  1. Close all the files and applications on the disk that you want to repair.
  2. Open Disk Utility and select the disk in the list on the left.
  3. Click First Aid.
  4. Click the button to verify or repair the disk or disk permissions.

Check the S.M.A.R.T. status of your hard disk at the bottom of the window. If it shows "Verified," the disk has nothing wrong at this time. If you see "About to Fail" in red letters, back up your files on the disk as soon as possible and replace the disk.

See also

repairing disks

Testing and repairing your startup disk

Checking the S.M.A.R.T status of your hard disk

Open this for me

Disk Utility